Electro-hydraulic non-human braking systems for autonomous vehicles

Abstract

To provide an electro-hydraulic non-manpower braking installation (1) for a motor vehicle traveling autonomously.SOLUTION: The invention proposes that a vehicle brake installation (1) can be operated by an auxiliary brake unit (3) when the auxiliary brake unit (3) is connected to a foot brake unit (2) and the foot brake unit (2) fails. In order to be able to generate brake pressure rapidly, by using the auxiliary brake unit (3), even in the case of cold and viscous brake fluid, the present invention contemplates a check valve (30) in the foot brake unit (2), and by the check valve, hydraulic pumps (22) of the auxiliary brake unit (3) are connected to a brake fluid reservoir (20) of the foot brake unit (2).SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an electro-hydraulic non-manual braking equipment for an automobile capable of autonomous driving, which has the constituent elements of the preamble of claim 1.

Background Art

[0002] For autonomous driving up to level 4 (where driver intervention can be requested) and level 5 (the highest level, where a driver is not required), a redundant non-manual vehicle braking equipment is required that can almost certainly eliminate a complete failure of the vehicle braking equipment with a probability close to certainty without requiring driver intervention.

[0003] Patent Document 1 discloses an electro-hydraulic non-manual braking equipment having a foot brake unit and a brake pressure control unit. The foot brake unit has a master brake cylinder operable by muscular force, and has, as a non-manual brake pressure generator, a piston-cylinder unit in which a piston is slidable in the cylinder via a screw drive by an electric motor, and is hydraulically connected in parallel to the master brake cylinder. A non-pressure brake fluid storage container is placed on the foot brake unit, to which the master brake cylinder and the non-manual brake pressure generator are connected. The brake pressure control unit has solenoid valves, and has a hydraulic pump for individual wheel brake pressure control in each brake circuit. The brake pressure control unit is connected to the foot brake unit, and the hydraulic wheel brakes are connected to the brake pressure control unit.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

[0005] The electro-hydraulic non-human-powered braking system according to the present invention, having the constituent elements of claim 1, is intended for autonomous driving up to Levels 4 and 5 on public roads. Level 4, also known as highly automated driving, means that the driving of the vehicle is constantly handled by an electronic system, and the driver is only requested to intervene if the system becomes unable to perform its driving role. Level 5, also known as fully automated, does not require a driver.

[0006] The vehicle brake system of the present invention having the constituent elements of claim 1 comprises a foot brake unit to which one or more hydraulic wheel brakes are connected, and an auxiliary brake unit. The wheel brakes are usually operated by the foot brake unit, which is called foot braking. To operate the wheel brakes, the foot brake unit comprises a brake pressure generator for generating brake pressure and one or more brake pressure control valve structures for controlling the wheel brake pressure in the wheel brakes. "Control" also means regulation. It is preferable that the wheel brake pressure is controlled individually for each wheel brake, but it is also possible to control the wheel brake pressure for a group of wheel brakes, or to control the wheel brake pressure of all wheel brakes together. The magnitude of one or more wheel brake pressures, and consequently the braking force of the wheel brakes, is controlled. Furthermore, one or more brake pressure control valve structures can also enable slip control, vehicle dynamic control (often called "side-skid control" in everyday language), automatic braking, and distance control.

[0007] The foot brake unit may have a muscle-force master brake cylinder or an auxiliary-force master brake cylinder as a brake pressure generator, the latter meaning a muscle-force master brake cylinder having, for example, a negative-pressure brake booster or an electromechanical brake booster. Auxiliary-force braking is distinguished from auxiliary braking by an auxiliary brake unit in the event of failure of the foot brake unit. As a supplement or replacement for the master brake cylinder, the foot brake unit may have a non-human-powered brake pressure generator, for example, a piston-cylinder unit in which a piston can slide within the cylinder via a rotation-translation-conversion gear, for example, by an electric motor. Another option for a non-human-powered brake pressure generator is, for example, a hydro pump that can be driven by an electric motor.

[0008] The auxiliary brake unit operates the wheel brakes in the event of a malfunction or failure of the foot brake unit. When the brake pressure control valve structure is functional, the wheel brake pressure in the wheel brakes can be controlled by the brake pressure control valve structure of the foot brake unit. Brake operation by the auxiliary brake unit in the event of a malfunction or failure of the foot brake unit is called auxiliary braking. To simplify the structure, it is not necessarily intended that the auxiliary brake unit have a brake pressure control valve structure, but embodiments of the present invention in which both the foot brake unit and the auxiliary brake unit have brake pressure control valve structures are also possible.

[0009] The auxiliary brake unit preferably has a non-manual brake pressure generator connected to the brake fluid storage container of the foot brake unit by a check valve located in the foot brake unit. This eliminates the need for the non-manual brake pressure generator of the auxiliary brake unit to draw brake fluid from the brake fluid storage container of the foot brake unit with high flow resistance by the master brake cylinder of the foot brake unit, in order to generate brake pressure during auxiliary braking. Instead, the check valve allows the non-manual brake pressure generator to draw brake fluid from the brake fluid storage container of the foot brake unit with low flow resistance. This improves the suction behavior and enables rapid brake pressure generation by the non-manual brake pressure generator of the auxiliary brake unit during auxiliary braking, especially with viscous brake fluid at low temperatures.

[0010] The dependent claims cover preferred embodiments and variations of the invention described in claim 1.

[0011] The foot brake unit and / or auxiliary brake unit each preferably have a hydraulic block. The hydraulic block is often a rectangular component and is usually made of metal, but may be made of other materials such as plastic. Blind holes are drilled in the hydraulic block to serve as housings for the hydraulic components of the vehicle brake system. Such components are solenoid valves, whose hydraulic portion is typically located in each housing of the hydraulic block, with electromechanical parts such as armatures and magnetic coils protruding from the hydraulic block. The hydraulic portion of a solenoid valve is the actual valve, i.e., a valve housing with a shield and a valve seat, for example. Other hydraulic components include, in particular, piston-cylinder units, hydraulic pumps, hydraulic reservoirs, check valves, and components of the pump drive unit. Furthermore, such hydraulic blocks have blind holes for connecting brake piping to hose nipples and push-in nipples ("self-clinching"). The blind holes forming the housings for the hydraulic components often have a stepped diameter. The hydraulic block is perforated so that the housings for the hydraulic components are connected to one another according to the hydraulic piping diagram of the vehicle brake system or foot brake unit and / or auxiliary brake unit, which can be called (hydraulic) interconnection. The perforations in the hydraulic block are often in Cartesian coordinates, that is, each hole is parallel and perpendicular to each other, and parallel and perpendicular to the faces and edges of the hydraulic block within the rectangular hydraulic block. The hydraulic block is equipped with hydraulic components, one or more electric motors to drive a non-human brake pressure generator, an electronic control device, etc., and constitutes a foot brake unit or auxiliary brake unit. "Equipped" means that the hydraulic components are located in the respective housings of the hydraulic block, and the electric motors and one or more control devices are located on the surface of the hydraulic block.

[0012] All constituent elements disclosed in the detailed description and drawings of the invention may be embodied in embodiments of the invention, either individually or, in principle, in any combination. Embodiments of the invention having only one or more constituent elements, rather than having all the constituent elements of a single claim, are also conceivable in principle.

[0013] Next, the present invention will be described in detail with reference to embodiments shown in the drawings. The drawings are as follows: [Brief explanation of the drawing]

[0014] [Figure 1] This is a pressure piping diagram showing the foot brake unit of an electrohydraulic non-manual braking system based on the present invention. [Figure 2] Figure 1 is a hydraulic piping diagram showing the auxiliary brake unit of an electro-hydraulic non-manual brake system. [Figure 3] This is a modified hydraulic piping diagram from Figure 1, showing the foot brake unit of an electro-hydraulic non-manual braking system based on the present invention. [Modes for carrying out the invention]

[0015] The electro-hydraulic non-human-powered braking system 1 according to the present invention, as shown in the drawings, is intended for automobiles, i.e., passenger cars, that can operate autonomously up to Level 4 or 5. Level 4 means autonomous driving where the driver may be asked to intervene, and Level 5, the highest level, means autonomous driving that does not require driver intervention.

[0016] The non-human-operated braking system 1 comprises a foot brake unit 2 and an auxiliary brake unit 3. The foot brake unit 2 is intended for braking, and the auxiliary brake unit 3 is intended for braking in the event of a malfunction or failure of the foot brake unit 2. A hydraulic wheel brake 4 is connected to the foot brake unit 2 via brake piping—four in this embodiment. The auxiliary brake unit 3 is connected to the foot brake unit 2 via brake piping, so that the wheel brake 4 can also be operated by the auxiliary brake unit 3. The foot brake unit 2 and the auxiliary brake unit 3 are each independent modules and may be located in different places, for example, in the engine compartment of a passenger car. The brake piping connecting the auxiliary brake unit 3 to the foot brake unit 2 will hereafter be referred to as supply piping V1, V2 and return piping R1, R2.

[0017] The vehicle brake system 1 according to the present invention is manufactured as a two-circuit brake system, and the brake units 2 and 3 are manufactured as two-circuit brake units. Each has two wheel brakes 4 attached to one brake circuit. The auxiliary brake unit 3 is connected to the foot brake unit 2 by supply pipes V1 and V2 and return pipes R1 and R2 in each brake circuit. The connection points of the supply pipes V1 and V2 and the return pipes R1 and R2 coincide in the foot brake unit 2 and the auxiliary brake unit 3, and are represented by the symbols V1, V2, R1 and R2.

[0018] The foot brake unit 2 has a piston-cylinder unit 5, the piston 6 of which is slidable within a cylinder 9 via a spindle drive 8 acting as a rotation / translation conversion drive, powered by an electric motor 7. The electric motor 7, spindle drive 8, and piston-cylinder unit 5 constitute a non-human brake pressure generator 10 of the foot brake unit 2 for generating brake pressure for foot braking. Foot braking is the normal intended braking operation. The non-human brake pressure generator 10 is connected to both brake circuits via a foot brake valve 11 between a separation valve 12 and an intake valve 13.

[0019] The foot brake unit 2 has an intake valve 13 and a discharge valve 14 for each wheel brake 4, which allows for individual control of the wheel brake pressure for each wheel brake 4. This makes it possible to control the wheel brake pressure of the wheel brakes 4, and consequently the braking force of the wheel brakes 4, without slippage during normal driving. Furthermore, slip control, such as anti-lock control, drive slip control, vehicle dynamic control (also commonly called side-skid control), automatic braking, and distance control are also possible. Such controls are well known and will not be explained in detail here. The intake valve 13 and discharge valve 14 can also be understood as wheel brake pressure control valve structures 13 and 14.

[0020] In addition to the non - human - power brake pressure generator 10, the foot brake unit 2 also has a master brake cylinder 15 that can be operated by muscle strength, and the wheel brake 4 is connected to this via a cut - off valve 12 and a suction valve 13. The foot brake unit 2 has a cut - off valve 12 in each brake circuit, and has a suction valve 13 and a discharge valve 14 for each wheel brake 4. The master brake cylinder 15 serves as a target value generator for the wheel brake pressure to be adjusted by the wheel brake 4 during foot braking in the case of driver operation. The brake pressure is generated by the non - human - power brake pressure generator 10 both during driver operation and during autonomous driving. During foot braking, the master brake cylinder 15 is hydraulically separated from the wheel brake 4 when the cut - off valve 12 closes.

[0021] As described above, the master brake cylinder 15 serves as a target value generator for the wheel brake pressure during foot braking in driver operation where the brake pressure is generated by the non - human - power brake pressure generator 10 of the foot brake unit 2. When the non - human - power brake pressure generator 10 fails, the brake pressure can be generated by operating the master brake cylinder 15. This is so - called auxiliary braking by muscle strength and the master brake cylinder 15, and thus can also be regarded as a muscle - strength brake pressure generator.

[0022] In order to push out the brake fluid from the master brake cylinder 15 when the cut - off valve 12 is closed and enable the movement of the piston of the master brake cylinder 15 and the brake pedal 16, the foot brake unit 2 has a pedal stroke simulator 17 connected to the brake circuit of the master brake cylinder 15 via a simulator valve 18. The pedal stroke simulator 17 is a piston - cylinder unit having a piston that is spring - biased or, for example, gas - pressure - biased.

[0023] In the illustrated embodiments described in the present invention, the isolation valve 12 and the intake valve 13 are 2 / 2-way solenoid valves that open when in their respective non-energized basic positions, and the foot brake valve 11, the discharge valve 14, and the simulator valve 18 of the non-manual brake pressure generator 10 are 2 / 2-way solenoid valves that close when in their respective non-energized basic positions.

[0024] The hydraulic components of the foot brake unit 2 of the electro-hydraulic non-manual brake equipment 1 according to the present invention, namely the valves 11, 12, 13, 14, 18, the non-manual brake pressure generator 10, the master brake cylinder 15, the pedal stroke simulator 17, and other components, such as pressure sensors, etc., are arranged in the accommodating portion of the hydraulic block 19 of the foot brake unit 2, and are connected to each other according to the illustrated hydraulic circuit diagram of the vehicle brake equipment 1 or the foot brake unit 2 by perforations in the hydraulic block 19.

[0025] A brake fluid reservoir 20 without pressure, known from conventional master brake cylinders, is placed on the hydraulic block 19, to which the master brake cylinder 15 is connected, and the non-manual brake pressure generator 10 is connected by a check valve 28. A test valve 21 is provided between the brake fluid reservoir 20 and the master brake cylinder 15 in one of the two brake circuits. The test valve is, in this embodiment, also a 2 / 2-way solenoid valve that opens when in its non-energized basic position. A check valve 29 that can flow through in the direction of the master brake cylinder 15 is hydraulically connected in parallel to the test valve 21, although this check valve does not exist in all embodiments of the present invention.

[0026] The auxiliary brake unit 3 has a hydraulic pump 22 that can be driven by a common electric motor 23 in each of its two brake circuits. The hydraulic pump 22 is a piston pump, although other hydraulic pumps, such as gear pumps, etc., are also possible. The hydraulic pump 22 constitutes a non-manual brake pressure generator 24 together with the electric motor 23.

[0027] The suction side of the hydro pump 22 of the auxiliary brake unit 3 is connected to both brake circuits of the master brake cylinder 15 of the foot brake unit 2 via the suction valve 25 and the brake piping already mentioned, i.e., via the supply piping V1 and V2 to which the auxiliary brake unit 3 is connected to the foot brake unit 2. The pressure side of the hydro pump 22 of the auxiliary brake unit 3 is connected to both brake circuits of the master brake cylinder 15 of the foot brake unit 2 via the pressure valve 26 and the supply piping V1 and V2. Furthermore, the pressure side of the hydro pump 22 of the auxiliary brake unit 3 is connected to the separation valve 12 of the foot brake unit 2 via the brake piping, i.e., via the return piping R1 and R2 to which the auxiliary brake unit 3 is connected to the foot brake unit 2. Thus, the wheel brake 4 can be operated by generating brake pressure in the hydro pump 22 of the auxiliary brake unit 3, which constitutes a non-human-operated brake pressure generator 24. The wheel brake pressure in the wheel brake 4 can be controlled by the intake valve 13 and discharge valve 14 of the foot brake unit 2, which constitute the wheel brake pressure control valve structure, as long as these valves 13 and 14 and their control are functional. Brake pressure is generated by the hydro pump 22 of the auxiliary brake unit 3, which constitutes the non-human brake pressure generator 24, in the event of a malfunction or failure of the foot brake unit 2. This type of braking is called auxiliary braking.

[0028] In the illustrated embodiment illustrating the present invention, the suction valve 25 of the auxiliary brake unit 3 is manufactured as a 2 / 2-way solenoid valve that closes when in the unpowered basic position, and the pressure valve 26 is manufactured as a 2 / 2-way solenoid valve that opens when in the unpowered basic position. During auxiliary braking, the suction valve 25 opens, thereby allowing the hydro pump 22 of the auxiliary brake unit 3 to draw brake fluid from the brake fluid storage container 20 of the foot brake unit 2 through the master brake cylinder 15. Furthermore, the pressure valve 26 closes, biasing the wheel brake 4 with brake pressure.

[0029] When the foot brake is applied, the wheel brake 4 is biased by the brake pressure generated by the non-manual brake pressure generator 10 of the foot brake unit 2 through the open pressure valve 26 of the auxiliary brake unit 3 and the foot brake valve 11 of the foot brake unit 2 which should be opened in this case, or by the brake pressure generated by the master brake cylinder 15 through the open pressure valve 26 of the auxiliary brake unit 3 and the open separation valve 12 of the foot brake unit 2.

[0030] To rapidly generate brake pressure during auxiliary braking, the hydro pump 22, which constitutes the non-manual brake pressure generator 24 of the auxiliary brake unit 3, is connected in this embodiment to the brake fluid storage container 20 of the foot brake unit 2 by a check valve 30 located on the hydraulic block 19 of the foot brake unit 2.

[0031] An embodiment of the electrohydraulic non-manual brake system 1 according to the present invention is also possible, in which only one of the two check valves 30 is located between the brake fluid storage container 20 and the hydro pump 22 of the auxiliary brake unit 3, in which case the check valve 30 is located in the primary circuit and / or preferably in the brake circuit, which also includes a test valve 21. The primary circuit is the brake circuit that is directly operated by the brake pedal 16 via the pedal rod.

[0032] The check valve 29, which is hydraulically connected in parallel to the test valve 21 between the brake fluid storage container 20 and the master brake cylinder 15, can be omitted, especially when the hydro pump 22 of the auxiliary brake unit 3 is connected to the brake fluid storage container 20 of the foot brake unit 2 by the check valve 30 in both brake circuits.

[0033] The hydraulic components of the auxiliary brake unit 3, namely the hydro pump 22, valves 25 and 26, and other components such as pressure sensors, are located in the hydraulic block 27 of the auxiliary brake unit 3 and are connected to each other by perforations in the hydraulic block 27 in accordance with the hydraulic circuit diagram shown, which can also be called the interoperation of the hydraulic components 22, 25, and 26.

[0034] The brake fluid storage container 20 has chambers 31', 31''' for each brake circuit, and an additional chamber 31'' for the non-human-operated brake pressure generator 10 of the foot brake unit 2, i.e., it has a total of three chambers 31', 31'', 31'''. The check valve 30 to which the hydro pump 22 of the auxiliary brake unit 3 is connected to the brake fluid storage container 20 is connected to the same chamber 31' of the brake fluid storage container 20 as the test valve 21. The hydro pump 22 of the auxiliary brake unit 3 and both check valves 30 to which the hydro pump 22 of the auxiliary brake unit 3 is connected are connected to different chambers 31', 31'''' of the brake fluid storage container 20, respectively. The non-human-operated brake pressure generator 10 of the foot brake unit 2 is connected to its own chamber 31'', i.e., to a different chamber 31'' of the brake fluid storage container 20 than the hydro pump 22 of the auxiliary brake unit 3.

[0035] In comparison with Figure 1, Figure 3 shows that in this embodiment, the supply pipe V1 of one of the primary brake circuits is not directly connected to the brake fluid storage container 20 by a check valve 30, but rather passes through the master brake cylinder 15. In all other respects, Figures 1 and 3 are identical. [Explanation of Symbols]

[0036] 1. Non-human-operated braking equipment, vehicle braking equipment 2 Foot brake unit 3. Auxiliary brake unit 4. Hydraulic wheel brakes 10,15 Brake pressure generator 13,14 Wheel brake pressure control valve structure 20 Brake fluid storage container 21 Test valve 24 Non-human-powered brake pressure generator 29 Check valve 30 Check valve 31',31'',31'''' Chamber

Claims

1. An electro-hydraulic non-human-operated braking system (1) for an autonomous vehicle, comprising: a foot brake unit (2) having a brake fluid storage container (20), connected to at least one hydraulic wheel brake (4), and having brake pressure generators (10, 15) for generating brake pressure; and an auxiliary brake unit (3) connected to the foot brake unit (2), thereby allowing at least one of the wheel brakes (4) to be operated by the auxiliary brake unit (3) when the foot brake unit (2) fails, wherein the auxiliary brake unit (3) has a non-human-operated brake pressure generator (24) for generating brake pressure to operate at least one of the hydraulic wheel brakes (4), connected to the brake fluid storage container (20) of the foot brake unit (2) by a check valve (30), The foot brake unit (2) has a wheel brake pressure control valve structure (13, 14) for controlling the wheel brake pressure that biases at least one of the wheel brakes (4), The non-human-operated brake equipment (1) is characterized by having a plurality of brake circuits, and the auxiliary brake unit (3) has a plurality of non-human-operated brake pressure generators (24) connected to the brake fluid storage container (20) of the foot brake unit (2) by the check valve (30), each connected to a different brake circuit, wherein the non-human-operated brake equipment (1) has a plurality of brake circuits, and the auxiliary brake unit (3) has a plurality of non-human-operated brake pressure generators (24) connected to the brake fluid storage container (20) of the foot brake unit (2), wherein the electric hydraulic non-human-operated brake equipment (1) has a plurality of brake circuits, and the auxiliary brake unit (3) has a plurality of non-human-operated brake pressure generators (24) connected to the brake fluid storage container (20) of the foot brake unit (2) by the check valve (30), wherein the auxiliary brake equipment (1) has a plurality of brake circuits, and the auxiliary brake unit (3) has a plurality of non-human-operated brake pressure generators (24) connected to the brake fluid storage container (20) of the foot brake unit (2), wherein the auxiliary brake equipment (1) has a plurality of brake circuits, wherein check valve (30)

2. The check valve (30) is located in the foot brake unit (3), as described in claim 1, for the electrohydraulic non-manual brake system (1).

3. The electric hydraulic non-manual brake system (1) according to claim 1 or 2, wherein the foot brake unit (2) has a muscle-operable master brake cylinder (15), the master brake cylinder is connected to the brake fluid storage container (20) by a check valve (30), and the auxiliary brake unit (3) is connected to the master brake cylinder, so that the non-manual brake pressure generator (24) of the auxiliary brake unit (3) passes through the master brake cylinder (15) by the check valve (30) and is connected to the brake fluid storage container (20) of the foot brake unit (2).

4. The electric hydraulic non-manual brake system (1) according to any one of claims 1 to 3, wherein the foot brake unit (2) has a muscle-operable master brake cylinder (15) connected to the brake fluid storage container (20) by a test valve (21).

5. The electrohydraulic non-manual brake system (1) according to claim 4, wherein the brake fluid storage container (20) has a plurality of chambers (31', 31'', 31'''), and the check valve (30) is connected to the same chamber (31') as the test valve (21) of the brake fluid storage container (20).

6. The electrohydraulic non-manual brake system (1) according to claim 1, wherein the check valve (30) is connected to different chambers (31', 31'') of the brake fluid storage container (20).

7. The electrohydraulic non-manual brake system (1) according to any one of claims 1 to 6, wherein the brake fluid storage container (20) has a plurality of chambers (31', 31'', 31'''), the foot brake unit (2) has a non-manual brake pressure generator (10), and the non-manual brake pressure generator (10) of the foot brake unit (2) is connected to a chamber (31'') of the brake fluid storage container (20) that is different from the check valve (30).

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